My orders have been routed through ETRF, but nowadays they go through CDEL.
I can tell you this much. I'm just a small time trader and don't have nearly enough capital to short, which is what CDEL is known for.
"The “Three C’s”: Citadel Securities (CDEL), Canaccord Genuity (CSTI) and Cantor Fitzgerald (CANT) are almost always on a ticker together with the four more trusted sources mentioned above. While these “Three C’s” are rarely toxic diluters, they can be heavy short sellers at times, taking advantage of a good thing which is part of the game."
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